1991219 has 4 divisors (see below), whose sum is σ = 2096040. Its totient is φ = 1886400.

The previous prime is 1991189. The next prime is 1991239. The reversal of 1991219 is 9121991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9121991 = 1367 ⋅6673.

It is a cyclic number.

It is not a de Polignac number, because 1991219 - 2¹² = 1987123 is a prime.

It is a super-2 number, since 2×1991219² = 7929906211922, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52382 + ... + 52419.

It is an arithmetic number, because the mean of its divisors is an integer number (524010).

2^1991219 is an apocalyptic number.

1991219 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

1991219 is a deficient number, since it is larger than the sum of its proper divisors (104821).

1991219 is a wasteful number, since it uses less digits than its factorization.

1991219 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104820.

The product of its digits is 1458, while the sum is 32.

The square root of 1991219 is about 1411.1055949149. The cubic root of 1991219 is about 125.8074450297.

The spelling of 1991219 in words is "one million, nine hundred ninety-one thousand, two hundred nineteen".